This content originally appeared on DEV Community and was authored by Yogesh Bamanier
Learn how React leverages Virtual DOM and Fiber Node to efficiently update your UI and keep apps smooth. ✨
When I first started diving deep into React, I kept wondering: “Are Virtual DOM and Fiber Node the same thing?” 🤔
The short answer is no, but they are closely related, like two teammates ⚽ with different roles in a match.
🔹 Are They the Same? What’s the Relation? 🧩
- Virtual DOM (VDOM) 🖼️: a snapshot of your UI in memory.
- Fiber Node 🔗: the task manager for React, tracking updates to each component individually.
How they work together:
- When state or props change, React creates a new Virtual DOM tree 🌳
- React diffs the new VDOM with the previous VDOM 🔍 to detect changes
- Each detected change is represented as a Fiber Node (unit of work) ✂️
- Fiber schedules these updates incrementally on the main thread, deciding what to prioritize, pause, or resume 🕒
- The real DOM is updated smoothly without blocking the UI 🏗️
In short:
- VDOM calculates what to update
- Fiber decides how and when to update ⚡
🔹 Virtual DOM 🖼️
The Virtual DOM is an in-memory representation of the real DOM. React updates this virtual copy first, instead of touching the browser DOM directly.
How It Works:
- Render the UI to a Virtual DOM tree 🌳
- On state/props update, create a new Virtual DOM tree 🔄
- Diff the old and new VDOM to find changes 🔍
- Patch only the changed parts to the real DOM 🏗️
Pros:
- ⚡ Performance optimization – fewer direct DOM updates
- 🖌️ Declarative UI – React computes changes abstractly
- 🧠 Easier to reason about state updates and re-rendering
🔹 Fiber Node 🔗
Fiber is React’s reconciliation engine introduced in React 16.
Each component corresponds to a Fiber Node, a unit of work storing metadata like:
- 🏷️ Component type
- 📝 Props and state
- 🔗 Parent, child, sibling pointers
- ⚠️ Effect tags (tracking updates)
Why Fiber?
Previously, React’s diffing blocked the main thread ⏳ for large trees. Fiber solves this by:
- Splitting updates into small units ✂️
- Prioritizing important updates (animations vs background tasks) 🎯
- Pausing, aborting, or resuming work for smooth UIs 🛑➡️▶️
Example Fiber Tree:
App
├─ Header
│ └─ Logo
├─ Content
│ ├─ Article
│ └─ Sidebar
└─ Footer
Each node is a Fiber Node, with links to parent, child, and sibling Fibers 🔗.
🔹 Virtual DOM vs Fiber: Key Differences ⚔️
| Feature | Virtual DOM 🖼️ | Fiber Node 🔗 |
|---|---|---|
| Purpose | Represents UI in memory | Unit of work for incremental rendering |
| Updates | Synchronous diff & patch | Can be split, prioritized, paused, resumed |
| Performance | Reduces unnecessary DOM updates | Optimizes updates with scheduling ⚡ |
| Data Stored | Tree of React elements | Props, state, effect tags, pointers |
| Granularity | Whole tree diff | Node-level, fine-grained control 🧩 |
🔹 TL;DR Story 📖
I once faced a laggy React app 🐌 with heavy nested components. Using just the Virtual DOM was fine for small apps, but with hundreds of updates, the UI stuttered. Fiber’s incremental reconciliation saved the day 🎉, letting React pause low-priority updates and keep animations smooth.
🔹 Conclusion ✅
- Virtual DOM 🖼️: snapshot of your UI in memory
- Fiber Node 🔗: React’s task manager for smooth updates
- Together: VDOM calculates changes → Fiber schedules updates efficiently ⚡
This duo is why React can remain both declarative and high-performance, even in large apps.
Author: Yogesh Bamanier
LinkedIn: https://www.linkedin.com/in/yogesh-007/
I’ve saved this as a text document ready for editing in Markdown.
If you want, I can **also add a mini emoji-based flowchart inline**, showing **VDOM → Fiber → DOM updates**, to visually reinforce the relation. Do you want me to do that?
This content originally appeared on DEV Community and was authored by Yogesh Bamanier
Yogesh Bamanier | Sciencx (2025-09-23T19:32:51+00:00) ⚡ React Internals: Virtual DOM 🖼️ vs Fiber Node 🔗 for Performance Explained. Retrieved from https://www.scien.cx/2025/09/23/%e2%9a%a1-react-internals-virtual-dom-%f0%9f%96%bc%ef%b8%8f-vs-fiber-node-%f0%9f%94%97-for-performance-explained/
Please log in to upload a file.
There are no updates yet.
Click the Upload button above to add an update.